IO2 Experiments to determine 



were now closed up, it was necessary, in order to intro- 

 duce the powder into the chamber, to make it pass 

 through the vent, or to convey it through some other 

 aperture made for that purpose. The method I em- 

 ployed was as follows : a hole being made in the barrel, 

 about -j 2 ^ of an inch in diameter, a plug of steel was 

 screwed into this hole ; and it was in the center or axis 

 of the plug that the vent was made. To introduce the 

 powder into the chamber the plug was taken away. 

 The vent was made conical, its largest diameter being 

 inwards, or opening into the chamber; and a conical pin 

 of hardened steel was fitted into it, which pin was in- 

 tended to serve as a valve for closing up the vent, as 

 soon as the powder in the chamber should be inflamed. 

 To give a passage to the fire through the vent in enter- 

 ing the chamber, this pin was pushed a little inwards, so 

 as to leave a small vacuity between its surface and the 

 concave surface of the bore of the vent. 



But notwithstanding all possible care was taken in the 

 construction of this instrument to render it perfect in all 

 its parts, the experiment was as unsuccessful as the former: 

 upon firing the powder in the chamber (though it did 

 not fill more than half its cavity), the generated elastic 

 fluid not only forced its way through the vent, notwith- 

 standing the valve (which appeared not to have had time 

 to close), but it issued with such an astonishing velocity 

 from this small aperture, that instead of coming out 

 with a hissing noise, it gave a report nearly as sharp and 

 as loud as a common musket. Upon examining the 

 vent-plug and the pin, they were both found to be much 

 corroded and damaged ; though I had taken the pre- 

 caution to harden them both before I made the experi- 

 ment. 



